The use of inhalation devices in the administration of medicaments, for example in bronchodilation therapy is well known. Such devices generally comprise a body or housing within which a medicament carrier is located. Known inhalation devices include those in which the medicament is delivered in aerosol form, including the well known metered dose inhaler (MDI) delivery devices. Other known inhalation devices include those in which the medicament carrier is a blister strip containing a number of discrete doses of powdered medicament. Such devices usually contain a mechanism of accessing these discrete doses, usually comprising either piercing means or means to peel a lid sheet away from a base sheet. The powdered medicament can then be accessed and inhaled. Liquid-based inhaler devices are also known.
It is advantageous to provide the patient with a dose counter for counting the number of doses of medicament dispensed or still remaining. For flexibility, the dose counter should also be suitable for use with various types of medicament dispenser including those suitable for dispensing medicament in aerosol or powder form. It is also desirable that any counter be configured to register a count only when medicament is provided to the patient for inhalation, and in particular that opportunities for false counts and/or tampering are minimised. It is further desirable that the count be clearly visible by the patient.
The Applicants have now devised a dose counter that meets some or all of the above criteria. In embodiments, the dose counter may be provided to the medicament dispenser as a separable unit, which enables ready re-use and recycling thereof. The latter benefit is particularly important where the counter comprises components, which are readily re-usable and potentially expensive to re-manufacture.
The dose counter now provided has the advantage that it may be expressed in relatively compact forms and in particular, may be accommodated in a housing that is relatively thin (i.e. one that extends upwards in the direction of the axis defined by the counter wheels to only a minor extent). The counter herein may also be arranged to count over a relatively large count range (e.g. at least 120 counts).
U.S. Pat. No. 5,988,496 describes a dose counter comprising a first count wheel and second count wheel arranged to rotate about a common axis of rotation. The first count wheel includes a drive tongue that is movable between a rest position, in which it does not co-operate with the second count wheel and a drive position, in which it co-operates with the second count wheel to cause it to rotate about the common axis of rotation. The drive tongue is forced into position by action of a cam.
Applicant's co-pending PCT Application No. WO2005/079727 describes a dose counter for use with a medicament dispenser. The dose counter comprises a first count wheel arranged to rotate about a first axis of rotation, the first count wheel including a set of primary drive teeth arranged annularly thereon for drivable rotation of the first count wheel about the first axis of rotation; and a second count wheel arranged to rotate about the same first axis of rotation. A kick wheel is arranged to rotate about a second axis of rotation offset from the first axis of rotation and provides for intermittent motion of the second count wheel.